CN110784282A - A data reuse method for underwater acoustic communication based on soft information transfer - Google Patents

Abstract

The invention discloses a method for reusing underwater acoustic communication data based on soft information transmission, which is suitable for the field of underwater acoustic communication algorithm verification and data processing. The invention uses the probability likelihood function mapping method to map any information bit through modulation constellation points To the existing data, by equalizing and decoding the existing data, the likelihood ratio information of the existing data bits is obtained, and by designing the mapping form, the likelihood ratio of the existing data, that is, the soft information, is mapped to the newly designed information bits. , so that the new information bits are decoded by the decoding algorithm. Based on the existing real underwater acoustic data, the method of the invention can verify the performance of any coding scheme applied in the physical layer of underwater acoustic communication by means of soft information mapping without re-experiment, and is innovative in theory; The method of the invention can also save the huge consumption of manpower and material resources brought by the underwater acoustic communication sea trial experiment.

Description

A data reuse method for underwater acoustic communication based on soft information transfer

technical field

The invention relates to the field of underwater acoustic data reuse, in particular to an underwater acoustic communication data reuse method based on soft information transmission.

Background technique

The verification of the physical layer algorithm of underwater acoustic communication needs the experimental data of sea trial or lake trial as support. However, the cycle and cost of an underwater acoustic communication experiment is very huge. In addition, once the communication algorithm design is wrong, the received experimental data cannot be used, and the loss is huge. How to use the existing data to verify the newly proposed communication algorithm becomes very meaningful. The method of reusing underwater acoustic experimental data allows the data of one experiment to be reused, which will save tens of millions or even hundreds of millions of underwater acoustic experiment costs, and has very high academic and economic research value.

SUMMARY OF THE INVENTION

Aiming at the deficiencies of the prior art, the present invention proposes a method for reusing underwater acoustic communication data based on soft information transmission from the perspective of soft information transmission, which can meet the requirements of underwater acoustic communication experimental data verification of any coding algorithm.

The object of the present invention is achieved through the following technical solutions:

A method for reusing underwater acoustic communication data based on soft information transfer, characterized in that the method specifically comprises the following steps:

S1: encode the information bits b _k through different types of encoders, then perform interleaving and XOR operations, and map them to the existing data information bits p _k ;

S2: perform constellation point mapping on the existing data information bits p _k obtained in S1 to adapt to different signal-to-noise ratios to obtain a unified data symbol format f _k , and then output the data symbol format f _k through the underwater acoustic channel;

再经过均衡器，输出现有数据信息比特p_k的后验信息概率似然函数L_D(p_k)；S3: Obtain the existing standard transmission data constellation point at the receiving end

After passing through the equalizer, output the posterior information probability likelihood function L _D (p _k ) of the existing data information bits p _k ;

S4: Subtract the initial a priori information probability likelihood function L _A (p _k ) from the posterior information probability likelihood function _LD (p _k ) to obtain the external information probability likelihood function L of the existing data information bit p _{k E} (p _k ), and then de-XOR it with the check bit _sk to output

S5: Use the probability likelihood function _LE (d _k ) of the external information of the encoded information bits to be verified to perform symbol estimation and iterative update.

Further, the S1 is specifically:

(1) encoding the information bits b _k through the encoder to obtain the output uninterleaved encoded information bits c _k ;

(2) passing _ck through an interleaver to obtain interleaved coded bits _dk ;

(3) Perform an exclusive OR operation on the d _k and a set of check bits _sk to map the uninterleaved coded information bits _ck to the existing data information bits _pk .

Further, described S2 is specifically:

(1) constellation point mapping is carried out on the existing data information bits p _k to obtain a unified data symbol format f _k , and the mapping of constellation points adopts the principle of unified Gray code mapping;

(2) When the signal-to-noise ratio is less than 10dB, it is not enough for the high-order modulated constellation points to be equalized and decoded correctly, then the constellation points are remapped, and the existing data symbols f _k are mapped by symbol precoding m _k into a lower-order constellation point symbol g _k to increase the decision boundary, and then output through the underwater acoustic channel;

When the signal-to-noise ratio is greater than or equal to 10dB, no remapping of any constellation points is required, and the unified data symbol format f _k is directly output through the underwater acoustic channel.

Further, described S3 is specifically:

经过解预编码减m_k的操作得到现有数据符号f_k的估计值

当接收信号信噪比大于或等于10dB时，则直接得到现有数据符号f_k的估计值

(1) Identify the receiving standard data constellation points obtained through the underwater acoustic channel according to the S2 SNR classification. When the SNR of the received signal is less than 10dB, the received symbol

The estimated value of the existing data symbol f _k is obtained through the operation of deprecoding minus m _k

When the signal-to-noise ratio of the received signal is greater than or equal to 10dB, the estimated value of the existing data symbol _fk is directly obtained

经过均衡器，输出现有数据信息比特p_k的后验信息概率似然函数L_D(p_k)；(2) Estimated value of existing data symbol f _k

After the equalizer, the posterior information probability likelihood function _LD (p _k ) of the existing data information bits p _k is output;

Further, described S4 is specifically:

(1) Set the probability of the initial a priori information probability likelihood function L _A (p _k ) to be equal under each mapping constellation point;

(2) Subtract the original a priori information probability likelihood function LA (p _k ) from the posterior information probability likelihood function _LD (p _k ) obtained in S3 to _obtain the external information probability of the existing data information bit p _k Likelihood function L _E (p _k );

即：当s_k＝1时，L_E(d_k)变成自身的相反数，当s_k＝0时，L_E(d_k)保持不变。(3) Perform XOR operation on the external information probability likelihood function LE ( _{p k} ) and the check bit _sk , and output

That is, when _{sk =} 1, LE (d _k ) becomes the opposite of itself, and when _{sk =} 0, LE (d _k ) remains unchanged.

Further, described S5 is specifically:

(1) Pass the external information probability likelihood function _LE (d _k ) of the coded information bits to be verified through the deinterleaver ∏ ^-1 , and output the external information of the deinterleaver as the prior information probability likelihood function LA ( _{c k )} ;

(2) The prior information probability likelihood function L _A (c _k ) enters the maximum a posteriori probability decoder to obtain the decoded estimated value of the encoded bit to be verified and the posterior information probability likelihood function L _D (c _k );

(3) Subtract the prior information probability likelihood function LA (c _k ) from the posterior information probability likelihood function _LD (c _k ) to obtain the external information probability likelihood function _LE ( _{c k )} , and then After the interleaver ∏, the interleaved prior information probability likelihood function L _A (d _k ) is obtained;

(4) XOR the prior information probability likelihood function L _A (d _k ) with a set of check bits _sk to obtain the updated value of the prior information probability likelihood function L _A (p _k ) as The probability-likelihood function of the prior information for the next iteration of turbo equalization.

Compared with the prior art, the beneficial effects of the present invention are as follows:

(1) On the basis of the existing real underwater acoustic data, the performance of any coding scheme in the physical layer of underwater acoustic communication can be verified by means of soft information mapping without re-experimentation, which is innovative in theory;

(2) It saves the huge consumption of manpower and material resources caused by the underwater acoustic communication sea trial experiment, and has huge economic benefits.

Description of drawings

Fig. 1 is the system flow chart of the underwater acoustic communication data reuse method based on soft information transfer;

Figure 2 is a statistical graph of the bit error rate verified by the real sea trial experimental data.

Detailed ways

The present invention will be described in detail below according to the accompanying drawings and preferred embodiments, and the purpose and effects of the present invention will become clearer. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

As shown in Figure 1, a method for reusing underwater acoustic communication data based on soft information transmission specifically includes the following steps:

S1:

(1) the information bit b _k is encoded (convolutional code, Turbo code, LDPC code, Polar code) through the encoder to obtain the uninterleaved encoded information bit c _k of the output;

(2) passing _ck through the interleaver ∏ to obtain the interleaved coded bits _dk ;

(3) Perform an XOR operation on the interleaved coded bits d _k obtained in step (2) and a set of check bits _sk to map the uninterleaved coded information bits _ck to the existing data information bits _pk ;

S2:

(1) constellation point mapping is carried out on the existing data information bits p _k to obtain a unified data symbol format f _k , and the mapping of constellation points adopts the principle of unified Gray code mapping;

(2) When the signal-to-noise ratio (SNR) is less than 10dB, it is not enough for the high-order modulated constellation points to be equalized and decoded correctly, then the constellation points are remapped, and the existing data symbols f _k are precoded by symbols m _k is mapped to a lower-order constellation point symbol g _k to increase the decision boundary, and then output through the underwater acoustic channel;

(3) When the signal-to-noise ratio (SNR) is greater than or equal to 10dB, no remapping of any constellation points is required, and the unified data symbol format f _k is directly output through the underwater acoustic channel.

S3:

经过解预编码-m_k操作得到现有数据符号f_k的估计值

当接收信号信噪比(SNR)大于或等于10dB时，则直接得到现有数据符号f_k的估计值 (1) Identify the receiving standard data constellation points obtained through the underwater acoustic channel according to the S2 signal-to-noise ratio classification. When the received signal-to-noise ratio (SNR) is less than 10dB, the received symbol

The estimated value of the existing data symbol f _k is obtained through the deprecoding-m _k operation

When the signal-to-noise ratio (SNR) of the received signal is greater than or equal to 10dB, the estimated value of the existing data symbol _fk is directly obtained

经过均衡器，通过计算的方式，输出现有数据信息比特p_k的后验信息概率似然函数L_D(p_k)；(2) Estimated value of existing data symbol f _k

Through the equalizer, the posterior information probability likelihood function _LD (p _k ) of the existing data information bits p _k is output by means of calculation;

S4:

(1) Set the probability of the initial a priori information probability likelihood function L _A (p _k ) to be equal under each mapping constellation point;

(2) Subtract the original a priori information probability likelihood function LA (p _k ) from the posterior information probability likelihood function _LD (p _k ) obtained in S3 to _obtain the external information probability of the existing data information bit p _k Likelihood function L _E (p _k );

即：当s_k＝1时，L_E(d_k)变成自身的相反数，当s_k＝0时，L_E(d_k)保持不变。(3) Perform XOR operation on the external information probability likelihood function LE ( _{p k} ) and the check bit _sk , and output

That is, when _{sk =} 1, LE (d _k ) becomes the opposite of itself, and when _{sk =} 0, LE (d _k ) remains unchanged.

S5:

(1) Pass the external information probability likelihood function _LE (d _k ) of the coded information bits to be verified through the deinterleaver ∏ ^-1 , and output the external information of the deinterleaver as the prior information probability likelihood function LA ( _{c k )} ;

和后验信息概率似然函数L_D(c_k)；(2) The prior information probability likelihood function L _A (c _k ) enters the maximum a posteriori probability decoder to obtain the decoded estimated value of the encoded bit to be verified

and the posterior information probability likelihood function L _D (c _k );

(3) Subtract the prior information probability likelihood function LA (c _k ) from the posterior information probability likelihood function _LD (c _k ) to obtain the external information probability likelihood function _LE ( _{c k )} , and then After the interleaver ∏, the interleaved prior information probability likelihood function L _A (d _k ) is obtained;

(4) XOR the prior information probability likelihood function L _A (d _k ) with a set of check bits _sk to obtain the updated value of the prior information probability likelihood function L _A (p _k ) as The probability-likelihood function of the prior information for the next iteration of turbo equalization.

Figure 2 is a comparison chart of the bit error statistics of the real sea trial experimental data after data reuse and the bit error statistics without data reuse under the same data conditions. As can be seen from the figure, the higher the ratio of the histogram in the range of 0 to 10 ^-5 , the smaller the error range of the data packet; with the increase of the number of turbo iterations, the performance of the two methods increases accordingly, but the data The bit error rate of the utilization method is lower than that of the original equalization decoding, and the performance is better. Therefore, it is effective to explain the way of data reuse proposed by the patent.

Those of ordinary skill in the art can understand that the above are only preferred examples of the invention and are not intended to limit the invention. Although the invention has been described in detail with reference to the foregoing examples, those skilled in the art can still Modifications are made to the technical solutions described in the foregoing examples, or equivalent replacements are made to some of the technical features. All modifications and equivalent replacements made within the spirit and principle of the invention shall be included within the protection scope of the invention.

Claims (6)

1. A method for reusing underwater acoustic communication data based on soft information transfer is characterized by comprising the following steps:

s1: to transmit information bit b _kEncoding by different types of encoders, interleaving, XOR operation, and mapping to the existing data information bit p _k。

S2: the existing data information bit p obtained at S1 _kConstellation point mapping is carried out to adapt to different signal-to-noise ratios, and a uniform data symbol format f is obtained _kThen formatting the data symbol f _kOutput through an underwater acoustic channel.

S3: obtaining existing standard sending data constellation points at receiving end

Then outputs the existing data information bit p through the equalizer _kIs a posteriori information probability likelihood function L _D(p _k)。

S4: probability likelihood function L of posterior information _D(p _k) Subtracting the initial prior information probability likelihood function L _A(p _k) To obtain the existing data information bit p _kIs a probability likelihood function L of the extrinsic information _E(p _k) Then it is summed with the check bit s _kPerforming XOR operation and outputting

S5: probability likelihood function L of external information by using coded information bit to be verified _E(d _k) And performing symbol estimation and iterative updating.

2. The method for reusing underwater acoustic communication data based on soft information transfer according to claim 1, wherein the S1 specifically includes:

(1) to transmit information bit b _kCoding the data by a coder to obtain the output non-interleaved coded information bit c _k；

(2) C is to _kThrough the interleaver, the interleaved coded bit d is obtained _k；

(3) D is to be _kAnd a set of check bits s _kPerforming XOR operation to obtain non-interleaved coded information bits c _kMapping to existing data information bits p _k。

3. The method for reusing underwater acoustic communication data based on soft information transfer according to claim 1, wherein the S2 specifically includes:

(1) will have the existing data information bit p _kConstellation point mapping is carried out to obtain a uniform data symbol format f _kThe mapping of the constellation points adopts the principle of uniform Gray code mapping;

(2) when the signal-to-noise ratio of the signal is less than 10dB, the constellation point of the high-order modulation is not balanced and decoded correctly, remapping of the constellation point is carried out, and the existing data symbol f is used _kSymbol precoded m _kConstellation point symbol g mapped to a lower order _kSo as to increase the decision boundary, and then output through the underwater acoustic channel;

when the signal-to-noise ratio of the signal is greater than or equal to 10dB, the uniform data symbol format f is directly mapped without remapping any constellation point _kOutput through an underwater acoustic channel.

4. The method for reusing underwater acoustic communication data based on soft information transfer according to claim 1, wherein the S3 specifically includes:

(1) classifying the received standard data constellation points obtained through the underwater acoustic channel according to the signal-to-noise ratio of S2, and when the signal-to-noise ratio of the received signal is less than 10dB, receiving symbols

De-precoding minus m _kIs operated on to obtain the existing data symbol f _kIs estimated value of

When the signal-to-noise ratio of the received signal is greater than or equal to 10dB, the existing data symbol f is directly obtained _kIs estimated value of

(2) Existing data symbol f _kIs estimated value of

Outputting the existing data information bit p through an equalizer _kIs a posteriori information probability likelihood function L _D(p _k)；

5. The method for reusing underwater acoustic communication data based on soft information transfer according to claim 1, wherein the S4 specifically includes:

(1) setting an initial prior information probability likelihood function L _A(p _k) The probability under each mapped constellation point is equal;

(2) the posterior information probability likelihood function L obtained in S3 _D(p _k) Subtracting the initial prior information probability likelihood function L _A(p _k) To obtain the existing data information bit p _kIs a probability likelihood function L of the extrinsic information _E(p _k)；

(3) Probability likelihood function L of external information _E(p _k) And a check bit s _kPerforming XOR operation and outputting Namely: when s is _kWhen 1, L _E(d _k) Becomes the opposite of itself when s _kWhen equal to 0, L _E(d _k) Remain unchanged.

6. The method for reusing underwater acoustic communication data based on soft information transfer according to claim 1, wherein the S5 specifically includes:

(1) probability likelihood function L for coding information bit external information to be verified _E(d _k) Through de-interleaver |/ ^-1And outputs the external information of the deinterleaver as a prior information probability likelihood function L _A(c _k)；

(2) Prior information probability likelihood function L _A(c _k) Entering a maximum posterior probability decoder to obtain a decoding estimation value of the code bit to be verified

And a posteriori information probability likelihood function L _D(c _k)；

(3) Then the probability likelihood function L of the posterior information is calculated _D(c _k) Subtracting a prior information probability likelihood function L _A(c _k) Obtaining probability likelihood function L of external information _E(c _k) Then the probability likelihood function L of the prior information after interleaving is obtained through an interleaver II _A(d _k)；

(4) Probability likelihood function L of prior information _A(d _k) And then with a set of check bits s _kCarrying out XOR operation to obtain a prior information probability likelihood function L _A(p _k) As the prior information probability likelihood function of the next Turbo equalization iteration.

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